A magnetic detection device includes a Hall element, a voltage amplifier, a voltage comparison circuit and a latch circuit. The Hall element outputs voltage corresponding to strength of magnetic field. The voltage amplifier amplifies the output voltage from the Hall element to output the amplified voltage. The voltage comparison circuit compares the amplified voltage and standard voltage (reference voltage) corresponding to a detection threshold to output an output signal which is processed as a binary signal corresponding to a signal that magnetic field is formed or not. The latch circuit retains the output signal from the voltage comparison circuit. Further, the magnetic detection device can include a switch circuit which inverts polarity of the amplified signal.
The Hall element, a driving circuit and the like in the magnetic detection device are integrated on a silicon chip to be miniaturized. The magnetic detection device is called as a Hall IC in which a method to intermittently operate the Hall element by pulse-driving is often employed for lowering the consumption power.
When electrical current flows in the Hall element and the amplifier of the magnetic detection device as the intermittent operation, the power is largely consumed. On the other hand, the consumption power is suppressed in a case without applying electrical current. In other words, the decrease of the consumption power in the magnetic detection device can be attained just for an amount of an operation duty intermittently decreased.
However, the magnetic detection device has been installed in a digital assistant or the like such as a cell phone, a personal PC, a digital camera, a digital video camera and the like, so that consumption power of the magnetic detection device has been monotonically increased due to high functionalization and high performance. Consequently, the magnetic detection device has been further demanded to lower the consumption power.